Lead pot



Nov. 26, 1935. L H, HOPKINS 022,372

. LEAD POT l Filed July 24'a 1934 l I 1 l i l i i l i Q .E m @wir @9W 'ma '62 wmgf Patented Nev. '26, 1935 a UNITED l'STATI-:s PATENT. .orf-Ica l' 'Luthex'vllillopklnofoakllklll.y Application July 24,1934? Serial No. '138,651v

made of special heat-resisting alloys which, al-l though involving a much higher initial cost, are found to be more economicall on account of their much-longer life? Such pots, however, are subject to iailure due tocracking and breaking, and I have noted that such failures are more likely to occur in-cases where the lead pots aremot maintained under constant melting temperatures,

but have been allowed to cool from time izo-timeso that the lead bath therein becomes solidified and has to be again rehated to a moltenstate. I explain this, at least in part, by'theA fact that when heat is reapplied to a cold pot, the -high ,expansin of the lead as compared with that of the ferrous metal of which the pot is made (which is usually inthe ratio of about 5 to 1) causes severe stressesbetween the side walls of .the pot, which hasten failure and deterioration ofthe pot, so as to necessitate frequent replace-V ment thereof.. l

In carrying out my invention, Iprovide a new i apparatus, and method for protecting lead pots from the eifects of unequal expansion ot the bath material andthe container during intermittentsolidifying and reheating-of said bath material, which vconsistslzvroadly in providing a hollow yieldablememberroverlying one'or more upright- `walls ofsaid container while the bath is being cooled to a solid state, so thatwhen'the pot and bath are againreheated the excessive lateral exof the bath material is taken up by the 4'yieldable member.

certain practical methodsand Adevices mrearrying out my invention-will appear fromthe fol-A ,lowing description, reference being had to the accompanying drawing, in which l Fig. 1 Ls' a view iirvertical cross section of alead an expansion sleeve' has been ap-Vv pot to which A plied asan integral part thereof.`

2 is.a vshown inFig. I. Y

Fig. 3 is a cross section showing another -form of lead'pot and amodlifiedform or sleeve.-

Fig. 4

:isa-view in cross section of a lead'pot, n ow my invention may be utilized in the ing a flange I3 around horizontal cross section of the potform of a detachable inner sleeve, 5to befapplied toanordinaryleadpotcnlyatsuchtimesas whenthe bath is to be permitted to cool. .5 is a fragmentary view shpwing another forni-of pot, and including also arelatively large auxiliary for Supplying .bath materialduring the reheatingofsaid bath.

Fig. 6 is a view in horizontal section, showing a modified form of lead pot, in which a yieldable' chamber is applied to twoV sides of a' rectangular 10 Referring now to detalls of the several embodimmts of my invention illustrated in the drawing, agsimple form thereofis shown in- Figs. l and 2 in which a cylindrical lead pot 9 having a 15 flanged upper rim 1I may be made-of a'heat-re-w sisting steel alloy in the usualmanner. To this pot is'tted a metal inner shell or sleeve Ilfhavf its margin and welded along 'its periphery I3* to the flanged rim II of zo said pot.v The sleeve [2 is spaced from the side walls I0 of the pot so as to for'm a continuous l chamber-I4, and the lower edge Iiiof the sleeve extends almost to the bottom' ofthe pot. as shown, only enough opening being left along the 25 bottomto permit the molten bath material to flow -readily from the chamherlll into the main body of the pot, and vice Lversa. Inthe forni shown in Figs. 1' and 2, the inner sleeve I2"is corrugated in ross section as clearly shown ingFig. 2,. Means 3c for supplying gas or air to the chamber I4 is also provided', herein consisting of a supply Pipe I I connected'by nipple I6 to the upper end of the sleeve chamber IIL Said'inlet pipe I6 may have acontrol sure relief valve I9 therein, as shown in Fig. 1.-

The use and operationof the apparatus shown in Figs. 1 and 2 are as follows;

When it'is desired to permit the-lead bath to' cool and solidify inthe potya'uld such as ordi-f i0 nary citygas, or air, is admitted unde'ipressure 'the .supply pipe I6 inte the top er ehem# ber Il.' City gasma'y be preferably for thispur-y pose because it-is less likely to cause oxidation of thelad. 'Ihepressureoi the iluid is such asto 45` forceall the molten leadoutof the bottom of the valve I1; pressure gauge I8u'and apres- 35, v

until it is to be used again.

Now, when the pot is to be again put into use, it is reheated, while the pressure is relieved in the chamber I4 as by opening the relief valve I9.`

The initial expansion .of the solid lead will then 4be taken up by the inner sleeve I2 which is free to flex outwardly as required, thus relieving the high lateral stresses whichA otherwise would be eiective against the side walls of the pot.

In the form of apparatus shown in Fig. 3, Vthe upper margin 20 of the sleeve is shown as being welded to the inner face of the flange, and the lower portion of the sleeve is extended inwardly to a restricted opening 2| extending downwardly into a centrally disposed depression 22 formed in the bottomof the pot.

Another methodof use and application of my invention is illustrated in Fig. 4, in which a separate sleeve 2 5, having spaced inner and outer walls 26 and 21, is closed at the top but open at the bottom, as shown. Said sleevewis arranged to be detachably fitted into a pot I Iln of standard construction and suitably secured thereto as by a plurality of clamps- 28, engaging a flange 29 integral with said sleeve. With this arrangement,.the sleeve 25 may be applied to the pot only at such times as it is found necessary to permit said pot and its bath to cool, and

' said sleeve may then be entirely removed from the pot as soon as the bath is reheated to its f normal molten state. In other respects, the sleeve is employed in the same manner as previously described.

Fig. 5 illustrates a modified form of apparatus in which an auxiliary opening 30, normally closed by plug 3|, is provided, having suillcient size to permit an auxiliary charge of molten lead to be introduced'in, and partially ll, the

chamber I4 at the time the pot is being re'heated.`

With this arrangement, the added lead nlls the chamber I I so as to afford greater conductivity' of heat from the side walls of the pot and through the sleeve to the lead in the body of the pot and hasten the melting thereof, but the molten lead added to the chamber I4 as described, is free to rise, in said chamber so as to permit the desired excessive expansion of the solid lead mass within the pot during the initial heating thereof. I

Fig. 6 illustrates another application of my in- "vention, as it may be utilized in a rectangular pot III". In this form, only two ol' the upright walls of the pot are provided with yieldable par- Y Y reheating thereof, which consists in applying fluid :i

titions I2, I2, but said partitions will generally be suilcient to aiord-the desired protection from the eiects of lateral expansion of the lead while it is being reheated.

' Although I have shown certain forms and methods of application voi my invention, it will be understood that I do not wish to be limited to the specic forms or methods of use thereof disclosed herein, but that other modiiications may of unequal expansion o! said bath while the lat- -terY is being heated from solid to liquid state.

2. In combination with a container adapted to hold a molten bath, a partition supported 25 yieldably in spaced relation to an upright interior wall of said container to form a chamber com, municating with the interior of said containeradjacent the bottom thereof, and means for supplying iluid under pressure to said chamber. 3:)

3. The method of protecting molten bath containers from eil'ects of the unequal expansion and contraction of the bath material during intermittent solidifying ofsaid bath by cooling and under pressureto a chamber formed byv a partition yieldably supported in spaced relation relative to one or more upright walls of said container, said chamber being open at the bottom of said container, so as to expel the molten bath 4o from saidpchamber into the body of said container before said bath is cooled to a solid state.

4. The method ofprotecting molten bath containers from' eiIects of the unequal expansion and 45 contraction of the bath material during intermittent solidifying of said bath by`cooling and reheating thereof, which. consists in applying fluid under pressure to a chamber formed by a partition yieldably supported in spaced relation rela- 50 tive, to one or more upright walls of said container, said chamber being open at the bottom of said container, so as to expel-\-the bath molten from said chamber into the body of said container, and maintaining said pressure until the bath has been cooled to a-solid state.

LUTHER H. HOPKINS. 

